Battle of Baekgang

Over two days in early October 663, on the lower Geum River in south-western Korea, a Tang Chinese fleet allied with the kingdom of Silla destroyed a much larger Japanese fleet sent to save the Paekche (Baekje) restoration movement. Known in Japan as the Battle of Hakusukinoe, it crushed the last attempt to revive Paekche and ended Yamato Japan's military intervention on the Korean peninsula.

For centuries the peninsula was divided between Goguryeo, Paekche and Silla, whose alliances shifted often. Silla and Paekche worked together against Goguryeo from the late 420s until the early 550s, but in 553 Silla turned on its partner and took the whole Han River basin. Goguryeo, meanwhile, fought repeated wars with China's Sui and Tang dynasties.

In 660 a combined Silla and Tang army conquered Paekche. A Buddhist monk, Dochim, and the former general Buyeo Boksin launched a movement to restore the kingdom, bringing Prince Buyeo Pung back from Japan to be king and making the fortress of Juryu their base. After some early successes they were in serious trouble by 662, confined to Juryu and its surroundings, and Buyeo Pung had Boksin killed for fear of a revolt.

Paekche and the Yamato court of Japan had long been allies, and their royal houses were related; Paekche princes had lived at the Japanese court for generations. The loss of Paekche shocked Yamato. Empress Saimei (who had earlier reigned as Kōgyoku) and Crown Prince Naka no Ōe, the future Emperor Tenji, resolved to send help under the general Abe no Hirafu, and the empress moved her court to a temporary palace in northern Kyūshū to oversee the preparations. Around August 661 some 5,000 soldiers and 170 ships arrived, and in 662 further contingents of 27,000 and 10,000 men followed.

In 663 the Yamato fleet set out to carry troops up the Geum and relieve Juryu, which Silla forces were besieging. The Tang had placed 7,000 soldiers and 170 ships on the river to block them. On 4 October (27 August in the lunar calendar) the Japanese vanguard tried to force a way through, but the Tang ships held a tight, disciplined line and drove it off.

The next day Japanese reinforcements arrived, making their fleet several times larger than the Tang force. The river, however, was narrow enough for the Tang to cover their front and flanks as long as their line held. The Japanese attacked at least three times during the day and were repulsed each time. As they tired and their formation broke up, the Tang brought forward reserves, smashed both Japanese wings and hemmed the fleet in so that its ships could neither manoeuvre nor escape. Many ships were burned and sunk and many men drowned. The Japanese commander Echi no Takutsu was killed in close fighting. Japanese, Korean and Chinese sources all record heavy Japanese losses; the Nihon Shoki says 400 ships were lost.

The Paekche restoration movement collapsed, its lands were absorbed by the victorious alliance, and Yamato broke off relations with Silla. Historians have long wondered why Yamato committed so much to a war that did not touch its own territory. Explanations include the close ties between the two royal houses, the waves of elite refugees from the peninsula who had settled in Yamato since at least the 5th century, and the wish to keep a friendly kingdom on the peninsula after the loss of other allies. The linguist J. Marshall Unger has suggested on linguistic grounds that Paekche may have preserved a community related to the early speakers of Japanese.

Our 600 map shows the peninsula divided between Koguryo (Goguryeo), Paekche and Silla, with Yamato across the strait, as it stood before the war.